solar atmosphere

Definition

Astronomy

The part of the Sun above the visiblephotosphere, merging eventually into the solar wind. The solar atmosphere contains only a negligible fraction of the Sun’s mass and consists mainly of the chromosphere, the part of the atmosphere seen at solar eclipses and visible in between by users of special telescopes designed to cut out the Sun’s disc from view. The solar atmosphere is in constant motion, most notably a five-minute oscillation of its outer layers caused by pressure waves of energy resonating in the gas of the atmosphere. The outer part of the Sun’s atmosphere, the very low-densityCorona, has a temperature of up to about 2 million K, far higher than the surface temperature of even the hottest star. Much effort has been put into determining the composition of the Sun’s atmosphere from the strength of the spectral lines within it. This work has shown that within limits, it has the same composition as the most primitive classes of meteorite, which seem to be remnants of the solar nebula from which the solar system formed.